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MIG welding...setting the speed

I am new to the form. I have been using a stick welder for a while, repairing equipment on the farm. I have recently got a little mig welder.

I have only had it for a little while and welded a few exhausts. I really like using the MIG welder. How do i know to set the speed? Currently i just weld a little and adjust it till it goes good. It seems like if the speed is to slow it breaks the are and if it is to high there is a lot of splater.

Re: MIG welding...setting the speed

I'm not a short arc expert, had most experience with pulsed spray, so I believe these principles apply, but hopefully others will have more specific recommendations.
In general, wire feed speed = current = heat= penetration. Voltage = arc length, low voltage = too short and arc and wire stubs into base metal and makes a lot of spatter, high voltage = too long an arc and wire makes big globs and weld sucks. Attempt to tune in the sound of frying bacon. Also, the distance between the contact tip and the work affects how much current is lost to resistance heating of the wire, and how much current gets to the arc, so shorter distance is more heat to the arc so it should probably be around 1/2 to 3/4".

Thin materials require smaller wire and lower current.

Please tell us what power supply, what wire type and diameter, what shielding gas you are using.

Re: MIG welding...setting the speed

Let me clarify. I learned to stick weld when I was in high school on farm equipment. Welding is not my profession, just something that i like to do. The shop where work on equipment (fix things for use of heated garage and equipment) other than my cars has the following welders.

230volt ac/dc welder it is old and i think a Lincoln work great though
230 volt ac/dc lincoln that is newer and has selectable heat settings
Millermatic 200

My personnal welder is a Lincoln sp-135. My welder is for working on automotive problem. Putting in new sheet metal, Building exhaust (this welder works great) and i am planning to build a turbo header for my car this winter. I have a 91 940 turbo Volvo. I am a memeber of turbobricks.com (t760volvo is my name)

The purpose of my welder the sp-135 plus is for hobby welding on my cars.
I have .025" and my last tank was 25% CO2 75% aragon

Re: MIG welding...setting the speed

I also have question here.my welder a miller regency 250 with an old miller E51 feeder and an old airco spool gun.now the question,I do not have chart for amps and speed.some days I close my eyes and pick a number does anyone know where to get copy of a chart?would really apprecate it.

Re: MIG welding...setting the speed

Like everyone else said, frying bacon/smooth crackling is the sound you want .

New MIG welders usually make these common mistakes (I know I did!)-
too little voltage for the metal thickness (not enough penetration)...
moving the torch too fast (not enough penetration, skinny lumpy weld)...
too much wire speed for the voltage and travel speed (popping and spattering)...
holding the torch too far away from the work (black soot around the weld, spatter)...
holding the torch with too much angle to the work (similar results as holding it too far away). Hold the torch with the nozzle closer to vertical than horizontal...
and if you're use to stick welding, you may be 'pulling' the weld rather than 'pushing' it. MIG works best with the torch angled slightly so it points toward the direction of travel rather than away, opposite from stick welding.

Some solutions-
If your weld is tall and thin with little penetration, turn up the voltage or move the torch slower.
If it has good penetration but the wire is spattering alot, turn down the wire speed or move the torch faster.
If you have alot of black soot and spatter, you're probly holding the torch too far away from the work, or holding it with the nozzle laying down too much, or you need to turn up the gas flow, or a breeze may be blowing the gas away. Block the wind with your hand or body.

Re: MIG welding...setting the speed

lot of good tips.thank you.one question though if I am reading right you are saying if you have lot of black soot on piece being welded to turn up gas flow,is this correct? why I asking is I was told if you were getting lots of black soot to turn gas down.just like to know which is right,rember I'm a rookie

Re: MIG welding...setting the speed

Usually for me, black soot means insufficient gas coverage, which could be from a few things, one of which can be too low gas flow rate setting at the regulator. More often than that though, it's caused by a breeze blowing the gas away (usually caused by the fan I use to blow the smoke away) or an unclean gas nozzle (spatter sticks to the inside of the nozzle, builds up and restricts the gas flow). It can also be caused by holding the torch too far from the work, or holding the torch at too low an angle to the work. Unclean metal (including dirt, oil or paint in the weld area) and/or too much wire can also cause soot and spatter...

Re: MIG welding...setting the speed

I like to set the wire speed I want and adjust the volts until it runs smooth. The thinner the metal the lower the volts will have to be therefore the wire speed will have to lower as well. I listen for the hum. If the volts are too high it will almost scream and if too low it will almost sound like a car that needs to down-shift